Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight, Scrapyard Recombiner, and Yahenni, Undying Partisan

Prerequisites

• Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight on the battlefield
• Scrapyard Recombiner on the battlefield
• Yahenni, Undying Partisan on the battlefield

Steps

1. Activate Yahenni by sacrificing Scrapyard Recombiner
2. When Scrapyard Recombiner dies, its modular ability and persist ability trigger
3. Resolve the modular trigger, putting Scrapyard Recombiner's +1/+1 counters on another artifact creature
4. Resolve the persist trigger, returning Scrapyard Recombiner from your graveyard to the battlefield
5. It will not have a -1/-1 counter on it due to its modular ability
6. Resolve the Yahenni ability
7. Repeat

Results

• Infinite LTB
• Infinite ETB
• Infinite sacrifice triggers
• Infinite death triggers
• Infinite +1/+1 counters on artifact creatures you control